Form index pulse generator

ABSTRACT

An improved tapeless format control system for a line printer is provided which will control the pitch between printed lines on various length web paper forms. The system includes a stepping motor for driving a paper advance mechanism; gating circuitry associated with a novel gearing mechanism for selecting the desired one of a plurality of form lengths; a plurality of photo cells and light sensing devices associated with the stepping motor and with the paper advance mechanism; and logic circuitry cooperating with the photo cells and sensing devices and with the form length selecting mechanism in response to two different types of spacing instructions to provide a wide variety of printing formats on a variety of form sizes to thereby assure optimized flexibility in printing with the line printer.

United States atent [191 Hoffman 1 1 FORM INDEX PULSE GENERATOR [75] Inventor: Paul R. Hoffman, Chantilly Va.

[73] Assignee: Burroughs Corporation, Detroit,

Mich.

[22] Filed: Oct. 31. 1973 1211 Appl. No.: 411,317

[52] US. Cl. 318/696, 197/133 R [51] int. Cl. G051) 19/20, G05b 19/40 [58] Field of Search 318/685. 696; 197/133 R,

[56] 7 References Cited UNlTED STATES PATENTS 774,910 11/1904 Crawford 74/348 X 882.968 3/1908 Ruck 74/348 912.736 2/1909 Ruck 74/348 X 1,206,043 11/1916 Slonecker 74/348 2.842.246 7/1958 Furman et a1 t. 197/133 R 3,123,195 3/1964 Hewitt et a1. 197/133 R 3.323.700 6/1967 Epstein et a1. 197/133 R 3.346.086 10/1969 Cralle et a1. t. 197/84 R 3.499516 3/1970 Schaal' 197/133 R 3502.190 3/1970 Smith 197/133 R 3586953 6/1971 Markkanen et a1 318/685 6| FIELD 1 LINE 164 1 Oct. 22, 1974 IBM Technical Disclosure Bulletin Overcoming Forms Length Limitations in Line Printers", Brown. Vol. 15, No. 4. Sept. 1972, pp. ll55l 157.

Primary Examiner-Robert K. Schaefer Assistant Examiner.lohn Feldhaus Attorney, Agent. or Firm-Edwin W. Uren; Edward G. Fiorito; Paul W. Fish 57 ABSTRACT An improved tapeless format control system for a line printer is provided which will control the pitch between printed lines on various length web paper forms. The system includes a stepping motor for driving a paper advance mechanism; gating circuitry associated with a novel gearing mechanism for selecting the desired one of a plurality of form lengths; a plurality of photo cells and light sensing devices associated with the stepping motor and with the paper advance mechanism; and logic circuitry cooperating with the photo cells and sensing devices and with the form length selecting mechanism in response to two different types of spacing instructions to provide a wide variety of printing formats on a variety of form sizes to thereby assure optimized flexibility in printing with the line printer.

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C COMMON HOME POSITIONIB.

CROSS REFERENCE TO A RELATED APPLICATION The present invention is related to and represents a further advancement over the tapeless format control apparatus described and claimed in patent application Ser. No. 366,122 filed by Paul R. Hoffman on June 1, 1973 and entitled A Tapeless Format Control System", and over patent application Ser. No. 396,353 filed by Paul R. Hoffman and Roger S. Naeyaert on Sept. 12, 1973 and entitled A Tapeless Paper Motion Control System Providing Sensing Circuits To Govern Motor Incrementing, both such applications being assigned to the assignee of the present invention.

FIELD OF THE INVENTION The invention relates generally to a format control system for line printers and more particularly to a tapeless format control system for controlling the advancement of web paper in a line printer.

BACKGROUND OF THE INVENTION As pointed out in connection with the disclosure of the above-referenced patent applications, many prior art printing system make use of prepunched paper tape loops to control the spacing and arrangement of printed information on paper forms. Such loops are generally provided with rows and columns of machine readable apertures which represent spacing and formatting control instructions, the tapes being selectively and individually installable in tape sensing devices in the printer where they are advanced in synchronism with the advancement of the web paper. During this synchronized advancement of the tape loops, the apertures therein are sensed by sensing means, whereupon pulses resulting therefrom are transmitted through appropriate circuitry to the web paper advancing means of the printer, the web paper advancing means being thereby controlled from a starting and stopping standpoint to produce the desired arrangement of the printed information on the web paper forms. The control instructions represented by the apertures in the tape loops are generally combined with line selection instructions transmitted to the printer from a central processor or other extraneous control device.

Format control tapes of the kind commonly used in prior art line printers, and in format control apparatus forming a part thereof, have generally been characterized by two different categories of problems, a first catcgory involving the operational characteristics of the apparatus used for sensing and advancing the tapes, and the second category involving the condition and storage requirements of the tapes themselves. Prominent among the first category of problems are the inertial tendencies frequently causing the start-up or stopping motion of the tape to either lag behind or to run ahead of the starting or stopping of web paper motion, thereby giving rise to the disruption of the required synchronization between the tape and the web paper. Included in the second category of problems, involving the tapes themselves, are the need of maintaining space-taking files for storing a plurality of tapes that are not in active usage, the tendency of the tapes to become worn and dilapidated through excessive use or misuse, and the likelihood of error in either punchably producing the tapes or in effecting installation thereof in the tape sensing and advancing apparatus.

Another problem that bears significantly on high speed line printers, as opposed to low speed line printers, is that form length selection devices that are primarily mechanical tend to be a limiting factor on the speed of the line printer itself and also the speed at which the form length may be changed.

SUMMARY OF THE INVENTION It is accordingly an object of the present invention to provide a tapeless format control system for use in high speed line printers, such system being completely reliable in operation and ideally flexible in its ability to produce the desired formatting of printed information on any desired form length.

Another object of the present invention is to provide an improved format control system wherein form length selection may be accomplished quickly and effectively without compromising the efficient operation of the line printer even in a high speed mode.

The present invention is directed to a tapeless format control system which in addition to the elements and features of the systems disclosed in the above referenced patent applications Ser. Nos. 366,122 and 396,353, includes an inventive gearing group and gating means associated therewith for selectively determining the length of the paper form upon which the printed information is to be arranged, and for sensing the passage of each unit of selected form length past the print station. The inventive form length selection gearing group and related sensing means representing the improvement provided by the present invention cooperate with an incrementally advanceable stepping motor, with a skip and line advance instruction storage means, with a plurality of pulse generating means for identifying each increment of a stepping motor motion and each increment of web paper advance, and with means for coordinating the stored spacing instructions with the indentifying pulses, such elements having been disclosed in patent application Ser. No. 366,122, and cooperate also with means for controllably retarding web paper advancement as a selected printing line approaches the print position, and with means for comparing the previous printing position with the selected printing position so as to allow further incrementing only when the preceding incrementing step has been successfully completed, such plurality of means having been disclosed in patent application Ser. No. 396,353, the effect of such cooperation being the precise and proper arrangement of the printed information on the selected form length according to a preselected format.

In the preferred embodiment of the invention, the aforementioned improved means for selectively determining the length of the form upon which the printed information is to be arranged is comprised of a plurality of varying diametered gears which are peripherally coupled to an incrementally driven paper-advancing shaft, each gear having one or more concentrically disposed slots, slot sensing means associated with each each gear, gating means slectively ORing combinations of the outputs of said slot sensing means for generating a pulse when each unit of associated form length has been advanced past the print station, switching means coupled to the gating means for selecting the desired form length, and manual means for moving the peripheral gears to a predetermined reference point as indicated by a signaling means.

BRIEF DESCRIPTION OF THE DRAWING These and other objects and advantages of the invention will become apparent from the following description when read in conjunction with the accompanying drawing FIGS. in which: i

FIG. 1 is a partial perspective view showing various of the elements of the inventive format control system in association with web paper advancing means in a line printer;

FIG. 2 is an elevational view of various of the elements shown in FIG. 1;

FIG. 3 is a table of form sizes coordinated with associated slot positions on the peripheral gears;

FIG. 4 is a schematic block diagram illustrating the logic circuitry of the inventive format control system;

FIG. 5 is a plan view of the adjustable dials shown in FIG. 1;

FIG. 6 is a view of a portion of the continuous web paper used in the line printer, separable form sheets thereof being represented by perforated lines and representative printing lines thereon being identified by a plurality of broken ines;

FIG. 7A is a schematic component diagram illustrating the sensing circuit of the format control system;

FIG. 7B is a schematic component diagram illustrating the step counter and compare unit circuits of the inventive format control system;

. FIG. 7C is a schematic component diagram illustrating the motor control unit of the format control system;

FIG. 8A illustrates the gray code as it appears on the slotted motor step disk;

FIG. 8B is'a table of the gray codes in binary form for one revolution of the slotted motor step disk;

FIGS. 9A and 98 represent a table of the coded counting sequence for the step counter as it counts down from a given initialized position, representing a line instruction, to a common home position; and

FIG. 10 is a schematic component diagram illustrating the inventive form length selecting unit of the improved format control system.

DESCRIPTION OF THE PREFERRED EMBODIMENT The improved tapeless format control system of the 7 present invention is comprised of a stepping motor for incrementally advancing the web paper, gating means associated with -a gearing group for selectively determining the length of the paper form upon which the printed information is to be arranged and for sensing the passage of each unit of selected form length past the print station, a plurality of pulse generating means for identifying each increment of rotational motion of the stepping motor and each increment of advancement of the web paper, means for receiving and storing externally originated skip and line advance spacing instructions, and means for controllably coordinating the skip and line advance instructions with the plurality of identifying pulses and with signals from the form length selecting unit such that each line ofinformation printed on the selected form length is properly spaced fromthe preceding lines, such instruction and pulse coordinating means including means for controlling the increstep is dependent upon the successful completion of the preceding step, and means for retarding the speed of the stepping motor as it approaches a selected print position such that paper advancement is brought to a precise stop. Each of these broadly defined elements of the inventive format control system will be hereinafter described from a structural and functional standpoint, with reference to the accompanying drawing figures.

As illustrated in FIGS. 1 and 4, a stepping motor 16 fixed to the framework (not shown) of a line printer is provided with an incrementally rotatable motor shaft 20 to the outermost extremities of which are fixed a photocommutator disk 18 disposed in cooperating relationship with a sensing device 22, and a toothed pulley 21 which is coupled to a predeterminately larger toothed pulley 23 by means of a belt 14. The pulley 23 is fixed to an extremity of a paper advance shaft 12 which is provided with fixed and spaced-apart sprockets 10, the extending teeth of the sprockets 10 being cooperably engageable with perforations 13 arranged along the outermost edges of the web paper 24;

Means illustrated at 27 in FIGS. 1 and 2, and in block form in FIG. 4, which is effective for selectively determining the length of the paper form upon which the printed information is to be arranged, is comprised of four variously diametered gears 30-30, configured about and peripherally driven by an elongated widefaced gear 28 fixed to the rightmost extremity of the shaft 12. The peripheral gears 30-30.are fixed to shafts 32-32', respectively, journaled in a frame member 34.

In the preferred embodiment of the invention, the circumference of each peripheral gear 30-30"' is directly proportional to the largest form size associated with that peripheral gear 30-30', hereinafter referred to as the primary form size. Selected submultiples of the circumference of each peripheral gear 30-30 are likewise directly proportional to submultiples of the primary form size. Each peripheral gear 30-30 is provided with oneor more concentric rings 38-38 along which one or more slots 40 are positioned (FIG. 3), the positioning of more than one slot 40 along a given ring 38 or 38' being such that the slots are equidistant from each other in regards to the radians of rotation required of a peripheral gear 30-30 to bring a new slot 40 past a common reference point. In the preferred embodiment, the common reference point for the peripheral gears 30-30 in a series of sensing devices 39-39 each comprised of from one to a cluster of four photo-cell packages, as illustrated in FIG. 10, such photo-cells being radially positioned adjacent to the rings 38-38 of the peripheral gears 30-30'. Outputs signals from the photo-cells clusters are combinationally gated together in associated logic blocks 4646"' by one or more NOR-NAND gate sets 4444, as also illustrated in FIG. 10.

The gated set 44 associated with the outermost slotted ring 38 will output a signal on line 48 whenever the radians of rotation proportional to a primary form length have been completed by the associated peripheral gear 30-30. For those peripheral gears 30, 30, 30"having slotted rings 38 for form lengths that are submultiples of the primary, appropriate gated sets 44' will output signals on lines 48' whenever the radians of rotation proportional to a submultiple form length are completed by the associated peripheral gear 30-30'.

has a movable arm 54 which is connected to the leftmost end of a shaft 59. The rightmost end of the shaft 59, which extends through the wall 34 (FIG. 2) is pro vided with a knob 41 (FIG. 5) for form length selection. Selection of a given form length from a fixed set of form lengths defined to be 3 inches, 3 /2 inches, 3% inches, 4% inches, 5 /2 inches, 5% inches, 7 inches, 8 /2 inches, ll inches, 14 inches and 17 inches is accomplished by manually rotating the dial 41 to bring the indication mark corresponding to the given form length into alignment with a single mark on a cursor 33 and to rotate the movable arm 54 shown in FIG. to a correspondingly selected terminal 50 of the rotary switch 52. Only signals on lines 4848' entering the selected terminal 50 will flow through the arm 54 to be outputted on lines 75 and 56, the line 75 also being shown connected to the form selector 27 in FIG. 4.

After selecting the desired form length by means of the dial 41, it is necessary to rotate the peripheral gear 3030"' corresponding to the selected form length to an initializing reference point representing its selected home position. Means for accomplishing this initializing rotation of the selected gear 30-30 is provided in the form of a knob 36 (FIGS. 1, 2 and 5) fixed to an outer extremity of the shaft 32 extending through the wall 34, and a signalling device 58 shown in FIGS. 5 and 10. Rotation of the knob 36 is effective to directly rotate the gears 30', 30 and 30" by reason of their common coupling with the wide face gear 28, such rotation of the knob 36 continuing until the slot 40 of the selected gear 30-30 representing the selected form length is sensed by its associated photo-cell, whereupon a signal is outputted by the photo-cell through one of the lines 42 or 42' to the associated set of NOR-NAND gates 4444 and from said gates through the activated terminal 50 and arm 54 of the rotary switch 52 to the signaling device 58 along the line 56 (FIG. 10). In the preferred embodiment the signaling device 58 is an incandescent light source. Light from the signaling device 58 will serve to alert the operator that the peripheral gear 30-30 corresponding to the desired form length is in its home position.

It is to be noted that a disconnected clutch 35, see FIG. 4, is provided intermediate to the paper advance shaft 12 and the wide-faced gear 28 to permit rotation of the dial knob 36 and peripheral gears 30-30' without disturbing the position of the shaft 12 or the web paper 24.

The aforementioned plurality of pulse generating means forming a part of the present invention includes the above described peripheral gears 30-30' with their slotted rings 38-38, a double ringed multi-slotted photocommutator disk 18 shown in FIGS. 1, 4 and 8A fixed to the motor shaft 20, and a multi-slotted disk 26 shown in FIGS. 1, 2 and 4 fixed to the paper advance shaft 12 intermediate the disconnected clutch 35 and the wide-faced gear 28, the disk 18 being associated with a sensing device 22, and the disk 26 being associated with a sensing device 25. Each of the sensing devices 22, 25, 39, 39', 39" and 39" is provided with one or more well-known light emitting elements or photo cells disposed on one side of its associated slotted disk or gear and a corresponding number of light sensitive switches disposed on the other side of the disk or gear, such elements being effective for pulsably sensing the passage of a slot therebetween. As best shown in FIG. 8A, the double ringed multislotted photocommutator disk 18, identified hereinafter as the motor step disk, is provided with 24 equally spaced-apart coded positions in gray code per ring where the coded positions contain up to 12 slots per ring and the multislotted disk 26, identified hereinafter as the field mark disk, is provided with 16 equally spaced-apart radial slots. In the preferred embodiment of the invention, each ring of coded positions of the motor step disk 18 is operatively sensed by its own photo cell and associated light sensing switch or sensor 27' of the sensing device 22, thereby providing for the generation of up to 24 codes per ring for each revolution of the motor shaft 20, each of such codes (resulting from the presence or absence of a slot) representing an incremental step of motor shaft movement equal to a 15 angular displacement thereof. The predetermined relative diameters of the motor shaft pulley 21 and the pulley 23 of the shaft 12 are such that each 15 increment or step of motor shaft movement will produce l/120 inch of web paper advancing movement, a complete revolution of the motor shaft thereby producing 1/5 inch of paper advancement. In the preferred embodiment, also, the diameters of the sprockets 10 on the paper advance shaft 12 have been so predetermined that one revolution of the shaft 12 will produce eight inches of paper advancement. It can thus be seen that each of the 16 pulses generated during each revolution of the paper advance shaft 12, by reason of the 16-slotted field mark disk 26 fixed thereto, will serve to represent and to identify a /2 inch incremental advancement of the web paper.

The previously mentioned means for receiving and storing skip and line advance spacing instructions from a central processor is comprised of a shift register 64 shown in FIG. 4, such register consisting of a five-digit field advance instruction portion and a four-digit line advance instruction portion, the five digit of the field instruction portion representing the binary decimal digits 1, 2, 4, 8 and 16, and the four digits of the line instruction portion representing the binary decimal digits 1, 2, 4 and 8. It will thus be seen that the field instruction portion of the register 64 will be effective to receive and store 32 separate codes to provide for /2 inch incremental advancements of the web paper, and that the line instruction portion will be effective to receive and store 16 separate codes to provide for various l/ I 20 inch incremental advancements of the paper, the latter incremental advancements being explained hereinafter in connection with the previously mentioned broadly defined means for controllably coordinating the skip and line advance instructions with the plurality of identifying pulses.

FIG. 4 is illustrative of the means for controllably coordinating the skip and line advance instructions stored in the register 64 with the plurality of identifying pulses generated by the forms index gears 30-30 (within the Form Selector 27), the field mark disk 26 and the motor step disk 18. A line decoder is coupled to the line instruction portion of the register 64 by lines 72, and coupled also to an encoder 94 by a plurality of lines 92. It is the function of the line decoder 90 to interpret Decoded Code instruction 0000 No advance 0001 Single space l-per-inch (S) 0010 Single space 8-pcr-inch (S8) 001 1 Single space 6-per-inch (S6) 0100 Double space l0pcrinch (D10) 0101 Double space 8-per-inch (D8) 0110 Double space 6-pcr-inch (D6) 01 l 1 Triple space l0per-inch (T10) 1000 Triple space 8-pcr-inch (TX) 1001 Triple space 6-per-inch (T6) 1010 Skip to Heading 1011 Skip to Bottom Remaining codes may be utilized for other desired line spacing instructions, such as four spaces at fi-per-inch. and six spaces at Spur-inch, etc.

The encoder 94, which is previously mentioned is coupled to the line decoder 90 by a plurality of lines 92, functions'to compute the number of 1/120 inch steps of the stepping motor 16 that will be required to produce thedesired line spacing represented by the particular code stored in the line instruction portion of the register 64 and interpreted by the line decoder 90, the computed value being then entered in a step counter 100. The following table will serve to reflect the number of l/ l 20 inch steps of the stepping motor that will be required to satisfy the various line spacing instructions interpreted by the line decoder 90.

In addition to the register 64, the line decoder 90, the encoder 94, and the step counter 100, the previously mentioned means for controllably coordinating the skip and line instructions with the plurality of identifying pulses also includes a field mark counter 76, a field compare unit 70, a compare unit 98, a motor control unit 66, and a sensing circuit 122 the function of which will be hereinafter described. It is to be noted from FIG. 4 that the field mark counter 76 is coupled to the form selector unit 27 by the line 75, and to the field mark disk 26 and its associated sensing device 25 by a line 74, and that the field compare unit 70 is coupled to the field instruction portion of the register 64 by a plurality of lines 68, and coupled also to the field mark counter 76 by lines 78.

. The field compare unit 70 is coupled to a motor stop and detent control 114 by a line 80, through a pair of NAND gates 84. The field compare unit 70 is also coupled to a flip flop 168 (FIG. 7A) of a Sensor Sensing Circuit 122 and the step counter 100 by a-line 82. It can I be seen from the above described couplings of the various elements that the field mark counter 76 is'reset by each pulse generated by the form length selector unit 27 and transmitted along the line 75, and is countably advanced by each pulse generated by the field mark disk 26 and transmitted along the line 74. It will be apparent that the field compare unit will function to continuously compare the accumulated count in the field mark counter 76 with the binary coded instruction stored in the field instruction portion of the register 64, and will transmit asignal indicating a true state along the line 80 to the NAND gates 84, and along the line 82 to the flip flop 168 of Sensing Circuit 122, whenever an equals or true state is detected therein.

The step counter is coupled to the motor step disk 18 and its associated sensing device 22 through the sensing circuit 122. The sensing circuit 122 as shown in FIG. 7A is comprised of a sensor gating circuit 124, a sensor storage circuit 126, a sensor compare circuit 128, and a pulse generator circuit -132. The purpose of the sensing circuit 122 is to allow the stepping motor 16 to increment only after successfully completing the previous increment of one forward step. Using signals on line 134 of the gating circuit 124 gained by sensing of the gray-coded slots on the motor step disk 18, combined with the stored signals on line 136 from the storage circuit 126, resulting from the previously sensed gray coded slots, will give a comparison signal on line 138 indicating a correct increment that will be unique to 60 of rotation of the motor step disk 18 in either direction. If there is an error condition, the sensing circuit 122 will not allow the stepping motor 16 to continue to rotate until a correct sensor comparison is made by the sensor compare circuit 128.

The sensor gating circuit 124 receives the separate gray coded signals generated by the sensing device 22 from the slotted'rings A and B of the motor step disk 18. FIGS. 8A and 8B show the gray coded slot arrangement of disk 18, and a table of the gray codes, respectively, inthe sequential order in which they will cyclically appear on the disk 18. These A and B signals on lines 101 and 101 respectively (FIGS. 4 and 7A) are further subdivided into lines 140 (FIG. 7A) for signal A on, signal A of signal B on, and signal B off by means of the lines and NAND gates of circuit 142. An additional plurality of NAND gates 144 are included using signals on lines 146 from the above subdividing circuit 142 as inputs to provide a unique signal on lines 134 for any combination of the A and B gray coded signals being sensed.

Another function of the sensor gating circuit 124 is to allow the subdivided signals on line 140, before printing isto begin, to initialize on lines 150 the flip flops 152 of a sensor storage circuit 126 through a series of NAND gates 148, whenever the skip'control circuit is enabled on line 96. Thus the electronics of the format control system will start out in sync with the stepping motor 16. Whatever gray coded position the motor step disk 18 is in at system start up time will be recorded in the sensor storage circuit 126.

The flip flops 152 of the sensor storage circuit 126 will be triggered by a signal on a line 154 from the pulse generator circuit 130-132 every time a'correct increment of the stepping motor 16 has been made and are so interconnected so as to have the immediately previously sensed gray coded signals as their respective states. The direct outputs on lines 156, 156, 156", 156" from these flip flops 152 are used as bias signals for the run and full-brake functions of the motor drive unit 66 to be explained hereinafter. Also, the outputs on lines 158 from flip flops 152 are gated in circuit 160 so that all possible combinations of two of their outputs may be represented by one unique signal on lines 162, 162', 162", 162', corresponding to previously sensed A and B gray coded signals as placed in the sensor storage circuit 126. Thus only one of these four sets of gates in circuit 160 will output at any given time on lines 162, 162, 162", 162'. These combined signals on lines 162, 162', 162" 162" are used in the motor control unit 66 for stop and brake-step biasing and additionally as inputs to the sensor compare circuit 128 as will be later explained.

The sensor compare circuit 128 functions to compare the sensor gating circuit signal on line 134 representing the presently sensed gray coded signal with the sensor storage signal on lines 162, 162, 162", 162" representing the immediately previously sensed gray coded signal. As an example of such comparison, with reference to FIGS. 8A, 8B and 7A, if the sensor storage circuit 126 has a signal A of and a signal B of 0 stored in it representing the immediately previously executed slot position, then the sensor gating circuit 124 should presently be receiving a signal A of0 and a signal B of 1 on lines 101 and 101 respectively in order for the sensor compare circuit 128 to output a signal on line 138. When the presently sensed signal is one step forward of the previously sensed signal then the sensor compare circuit 128 will output a signal indicating a good compare.

The pulse generator circuit 130-132 (FIG. 7A) serves as the source of trigger pulses for the flip flops 152 of sensor storage circuit 126 (along the line 154), and for the step counter 100 and the compare unit 98 (along line 170). The triggering input for the first stage 130 of the pulse generator circuits 130-132 itself is the clock of the central computer processor coming in on line 164 in the preferred embodiment. The bias for the first stage 130 of the pulse generator circuit 130-132 is received from the sensor compare circuit 128 on line 138. Since the trigger rate of the central processor clock is very much higher than the sensor compare circuit bias rate, as it is applied, the sensor compare circuit 128 bias application rate becomes defacto the pulse generator 130-132 circuit output triggerrate. The flip flops and associated NAND gates of the first stage 130 of the pulse generator circuit 130-132 will thus output trigger pulses to the second stage 132 of this circuit 130-132 on line 166, and also to the sensor storage circuit 126 on line 154, whenever a correct increment of the stepping motor 16 has been made, whether in execution ofa field or line instruction. It will be noted that the flip flops of this first stage 130 may be reset by a skip control signal on line 96. A flip flop 168 and associated NAND gates of a second stage 132 of the pulse generator circuit 130-132, on the other hand, will only begin outputting triggering pulses upon receipt ofa trigger pulse on line 166 from the first stage 130 and also of an initializing signal from the field compare 70 on line 82. It will be noted that the flip flop 168 is always grounded to its low state except when a line instruction is to be executed, at which point itis triggered by the first stage 130 and biased by a signal on line 82 to its high state to thereby output a signal on line 170. It will be noted that a signal on line 82 will only be present upon completion of a field instruction. The flip flop 168 will be reset back to its low state everytime a new signal is sent on line 61 to the register 64. The signal appearing on line 82 indicates completion of a field instruction and the permissive beginning of a line instruction. The pulse outputted on line 170 by the second stage is used to trigger the step counter 100 and also the braking circuit 180 of the compare unit 98 as will be explained hereinafter.

The step counter 100 of this system, as illustrated in FIG. 7B, is a six stage binary counter consisting of flip flops FF-l, FI -2, FF-4, FF-8, FF-16 and FF-32 going from low to high stages respectively, such counter having been designed to count down to a home position 173 in a binary manner as shown in the table in FIGS. 9A and 9B. At the beginning of a line instruction, the step counter 100 will be set by the encoder 94 on line 95 to whatever number of steps are required to accomplish the line instruction given in the register 64. Thus if SS-10 is desired as a line instruction, the step counter will be set to (011110) which is equivalent to twelve steps as shown at 171. As the stepping motor 16 begins incrementing for the line instruction, the step counter 100 will begin counting down at one count per completed step until the counter 100 reaches (101010) which is the common home position shown at 173 for all line settings of the counter 100, at which point the stepping motor 16 will lock into its stop position. The step counter 100 is reset to a zero state every time a signal appears on line 102, which is every /2 inch of paper advance as recorded by the sensing device 25. The encoder 94, on the other hand, is always outputting a setting signal on line 95. Thus at the beginning of an execution of a line instruction, the stepping counter 100 will be reset to zero by a signal on line 102. Next, initializing NAND gates 172 coupled to the line 95 will output control signals on lines 174 for the brief instant when an input signal is received on line 82 from the field compare 70, an input signal from the first stage is received on line 166, a low state signal from flip flop 168 is received on line 176, and encoder 94 signals are received on lines 95 such signals being received simultaneously to thus initialize on line 174 the step counter 100 to a value corresponding to the desired current line instruction as represented at 171 in FIGS. 9A and 9B.

As the step counter 100 is triggered by the pulse generator circuit 130-132 from its initialized line position to its home position, the compare unit 98 continuously samples the state of the step counter 100 on lines 99 and 99' and outputs function signals on lines 114, 114, 114", 114" to the motor control unit 66 reflecting the current step being processed. The step counter 100 outputs are NAND gated up through two distinct NAND trees 178 and 181 of the compare unit 98, the

first tree 178 for controlling the stop and run functions through stop and run control signals on output lines 114 and 114' respectively of the stepping motor 16, and a second tree 181 for controlling the braking circuit 180 of the stepping motor 16. At the top or output point of the first NAND tree 178, there are two separate output lines, one for stop on lines 110 and 114, and one for run on line 114' (FIG. 7C). In the time interval between the time the step counter 100 is initialized and the time at which the step counter 100 reaches its home position, the run signal along line 114 may be activated to merely indicate an absence of a stop signal on line 110, which in turn means that the home position has not yet been reached by the step counter 100, thereby allowing the stepping motor 16 to continue to increment. Once the step counter 100 has reached its home position (101010 in FIGS. 9A and 9B), the stop signal on line 114 will be outputted to disallow any incrementing by the Stepping motor 16. The stop signal on line 110 will continue to be outputted until the step counter 100 is reset to zero by a signal on line 102. The stop signal on line 110 is inputted into gating circuitry 179 (FIGS. 4 and 78) where the stop signal on line 110 is inputted to NAND gates 84 as is the field compare completion signal on line 80. Concurrent receipt of these signals will cause NAND gates 84 to output a motor stop and detent control signal on line 114 to the motor control unit 66.

At the top or output point of the second NAND tree 181 (FIG. 78), a signal outputted on line 182 by the final NAND gate in the tree will indicate that the stepping motor 16 is five steps away (010001) from its home position (101010) as determined from the outputs of the step counter 100. The signal outputted by the second tree line 182 is used for biasing the high input side of its associated flip flop 184. As this flip flop 184 is triggered by the high frequency central processor clock signal on line 164 (as was the first stage 130 of pulse generator circuit 130-132), application of bias by line 182 to the flip flop 184 will cause it to be almost immediately switched to its high state. As the low input side of the flip flop must receive a signal through an associated NAND gate that is the complete truth negation of the high input side signal in order to change its state, the flip flop then will only be triggered back to its low side upon a zero reset signal on line 102 as used by the step counter 100. The net result of this is that once the flip flop 184 has been set to its high side, it will stay there for the last five steps leading to the home position of the stepping motor. Once the flip flop outputs a signal on line 186 from its high side, a connected NAND gate 188 will deliver this signal to a point having a common terminal with the run signal line 114', thereby effectively cancelling the run signal when both are preset, the significance of which will be described more fully hereinafter. An additional NAND gate 188' is supplied with an input common to NAND gate 188 and whose inverted output is used to cancel any premature lock or stop signals on line 110 as a result of residue currents in the first NAND tree 178. Five steps away (177 in FIGS. 9A and 9B) from the home position was chosen as the requires to controllably retard the speed of the stepping motor 16 to prevent any overshoot or oscillation over or about the home position respectively. The braking circuit 180 in this embodiment comprises a delayed multivibrator (DMV) 183 and associated NAND gates for outputting a brake step function signal on line 114" and a full brake function signal online 114". The DMV 183 is biased by a signal on line 186 from the high side of flip flop 184. Once so biased, the DMV 183 will output a signal on line 194 upon receipt of a triggering pulse on line 170 from the second stage 132 of the pulse generating circuit 130-132 which corresponds to the beginning of each of the last five steps mentioned above. The adjustable period of the output signal on line 194 from the delayed multivibrator 183 will never be any longer than the shortest anticipated interval between increments of the stepping motor 16, or in other words, the fastest expected speed of the motor 16.

The output signal on line 194 from the DMV 183 will be inverted and shaped by an operatively coupled NAND gate 192 to become what is called a Full Brake Signal on line 114" (FIG. 7C) which is actually a reverse run signal in that the windings of the stepping motor 16 are excited in a mode reverse to that of the normal run mode, thereby giving a braking effect to a forward moving stepping motor 16 when activiated. As the stepping motor 16 begins to slow down as a result of the cancelling of the run-signal on line 114", and application of the full brake signalon line 114", the DMV 183 for a given adjustable output period, will begin to time out or be off for increasingly longer periods near the end of each step as the stepping motor 16 increments closer to the home position. This effect is taken advantage of by also feeding the output of the DMV 183 into its second series of associated NAND gates 190. These NAND gates 190 will be activated to output a signal on line 114" whenever concurrently the DMV 183 is not outputting a signal on line 194 and the flip flop 184 is outputting a signal on line 186. The signal outputting outputted by NAND gates 190 on line 114" is called a brake step and is used to power the stepping motor 16 in a manner similar to the run signal on line 114 except that only one of the four motor windings of the stepping motor 16 are excited at any given time. The purpose of this being to power the stepping motor 16 forward at a relatively low speed for increasingly longer periods as home position is approached, so that the stepping motor 16 is neither over or undershooting its home position. Once the home position is reached by the stepping motor 16, the first NAND tree 178 will become true and a stop signal on line will output to stop and lock the motor 16 in place, that is, the stator and rotor windings of the stepping motor 16 having like phases will line up with each other. The stop signal on line 110 through a NAND gate 196 will also cancel the full-brake signal on line 114" if there happens to be any residue left as outputted by the DMV 183 on line 194 when home position is reached, thereby preventing the stepping motor from backing away from home position. As can be seen from the above, the full-brake signal on line 114" will preempt the run signal on line 114', likewise the stepbrake signal on line 114" will pre-empt the full-brake signal on line 114', and finally the stop signal on line 110 will pre-empt the brake-step signal on line 114". In effect, the above function signals are exclusive ORed in that only one of them 'may be present at any given time.

The motor control unit 66 illustrated in FIG. 7C and consisting of gating and drive circuitry 199 will receive the function signals 114, 114', 114", 114" from the compare unit 98 and gate them with bias signals from the sensing circuitry 122. The result being that the direct bias signals on lines 156, 156', 156", 156",and combination bias signals on lines 162, 162, 162", 162" will indicate which phases of the four phase stepping motor 16 are available for performing the desired function at that point in time. The gating and drive circuitry 199 will allow only those phase windings having a concurrence of bias and function signals to be energized. Specifically, the gating and drive circuitry 199 is subdivided into four identical sets of NAND gates and drive units 198, 198', 198", 198', corresponding to the first, second, third and fourth phases respectively of the motor, Each of the sets of gates and drive units 198, 198', 198", 198", in turn, is provided with four identical NAND gates ORed together and corresponding to the four possible function signals outputted by the com pare unit 98, namely, run, stop, full brake and step brake. Each of the NAND gates of a set, if it is to output, must have a function signal from the compare unit 98 and a biasing signal from the sensing circuit 122. Thus, if the function desired is run or full-brake, then two different direct biasing signals on line 156, 156', 156", or 156" must be gated with the run or full-brake signal on lines 114' or 114" respectively in two different sets consisting of 198, 198', 198" I98 because the stepping motor 16 is designed to run or full-brake in a two phase mode. Additionally, the run signal on line 114, must be gated with a signal on line 62 indicating the presence of an instruction in order for the gate to be enabled. Likewise, if the function desired is step brake or stop, then one combination biasing signal on lines 162, 162, 162", or 162" from the flip flops 152 must be gated with the step-brakeor stop signals on lines 114" or 114 respectively in one of the sets consisting of 198, 198', 198 or 198" because the stepping motor 16 may only step-brake or stop in a one phase mode. Once a function NAND gate in a set has been activated, in a set consisting of 198, 198, 198 or 198', it will output a control signal on line 200, 200, 200" or 200" to its associated drive unit consisting of 202, 202', 202", or 202" respectively for that phase depending on the phase it is in. A drive unit consisting of 202, 202', 202" or 202" upon being switched on by such a control signal on line 200, 200', 200 or 200" will energize an associated winding of the stepping motor 16 through line 204, 204', 204", or 204" respectively to perform the desired function, be it run, stop, full brake or step brake.

A skip control unit 65 also shown in FIG. 4 is provided to enable slewing or skipping of the web paper in the absence of a field or line instruction code from the central processor along the line 61. A push button switch 63 coupled to the skip control unit 65 is manually operable to activate the stepping motor 16 along the line 62, an input being coincidentally transmitted along the line 96 to the NAND gates 118 and the step counter 100 to thereby reset the step counter and to initialize the circuitry 172 thereof. This manually initiated slewing will terminate when an enabling input signal is transmitted to the NAND gates 118 along the line 116, as generated by the slotted gears 3030" of the form selector 27 upon arrival of a selected gear at its above-defined home position, a stop pulse being thus passed and ORed to the motor stop and detent control 114. The NAND gates 118 also serve to activate the motor stop and detent control 114 in the normal execution ofa Skip to Heading instruction (binary code 1010 stored in the line instruction portion of the register 64), the line decoder 90 in such instance transmitting an input along the line 120 to the NAND gates 118, such gate being enabled upon receipt of an input along the line 116 upon arrival of the selected gear 30-30 in its defined home position, it being apparent that the defined home positions of the slotted gears 30-30' would represent the heading of the succeeding form.

OPERATION A full understanding of the operation of the inventive format control system is hereinafter conveyed with reference to FIG. 4, an initial phase of such explanation being of a generalized nature not involving the use of specific skip and line instruction codes, and a subsequent phase thereof describing how representative instruction codes would be utilized to effectuate printing on specified print lines.

It is to be noted before proceeding with this explanation that the field mark counter 76 is reset only at the beginning of each unit of selected form length, when the form selector unit 27 transmits a pulse thereto along the line 75, and that the step counter 100 is reset at the beginning of each V2 inch increment of paper advancement, when the field mark disk 26 transmits a pulse thereto along the line 102. It is accordingly also to be noted that the field mark counter 76 will accumulatively count a pulse from the disk 26 for the passage of each /2 inch vertical printing area on the sected form length, and that the step counter 100, when enabled by the flip flop 168, will count up to sixty l/ 1 20 inch increments of paper advancement between said /2 inch printing areas.

Upon setting the dials 36 and 41 (FIG. 5) to select a desired form length (between 3 inches and 17 inches in the preferred embodiment), a pulse is generated by the home positioned selected slotted gear 30-30' of the form selector 27 to thereby reset the field mark counter 76, and to transmit an input pulse along the line 116 to the NAND gates 118, the step counter 100 having already been reset by the preceding pulse from the field mark disk 26. Upon receipt of a field instruction code (other than 00000) in the five-digit field instruction portion of the register 64, along the line 61, (and with a 0000 code in the line instruction portion of the register) the motor 16 is activated to rotate the motor step disk 18 and the paper advance shaft 12, rotation of the shaft 12 being effective also for rotating the field mark disk 26 and the slotted gears 30-30'. As the field mark disk 26 rotates, the pulses generated by the radial slots therein will be counted by the field mark counter 76, each pulse representing and identifying a /2 inch increment of paper advancement. It is to be noted that during this advancement of the web paper, and counting of the field mark pulses by the counter 76, the pulses generated by the motor step disk 18 will not be counted by the step counter-100, since the flip flop 168 (FIG. 7A), which was de-enabled by the new instruction signal on line 61, has not again been enabled by an input from the field compare unit along the line 82. When the accumulated count in the field mark counter 76 is equal to the five-digit field instructon code in the register 64, the field compare unit 70 will transmit an input pulse along the line 80 to the NAND gates 84, such gate also having an input from the compare unit 98 along the line 110, by reason of the O-equals state of the step counter 100. Upon thus enabling the NAND gates 84, a stop pulse is transmitted and ORed to the motor stop and detent control 114 of the motor control 66, the motor being accordingly stopped for printing a line of information on the print line represented by the field instruction code stored in the register 64.

In the event printing is to occur in the first half inch of the selected form length, a line instruction code other than 0000 would be transmitted along the line 61 to the line instruction portion of the register 64 (with a 00000 in the field instruction portion of the register), whereupon the line decoder would serve to activate the selected line 92 corresponding to such line instruction code, the encoder 94 thereupon computing the number of motor steps of H inch each that are required to provide the desired line spacing, the value computed being entered in the step counter 100. Upon rotational activation of the motor 16, the motor step pulses generated by the disk 18 and the photo cells 22 would be transmitted along the lines 101 and 101' through the sensing circuit 122, along the line 170, if it is ascertained that a correct step has been made, to the step counter 100, the flip flop 168 having been enabled by an input along the line 82 from the field compare unit 70 by reason of the O-equals state of the field mark counter 76 and the field instruction portion of the register 64. When the count of the step counter 100 is equal to zero (or binary code 101010) representing the home position of the stepping motor 16, compare unit 98 .would transmit an input stop pulse along the line 110 through the NAND gates 84 to the motor stop and detent control 114, the NAND gates 84 being enabled by the presence of an input along line 80 from the field compare unit 70, also be reason of the O-equals state of the field mark counter 76 and the field instruction portion of the register 64. Upon activation of the motor stop and detent control 114, the motor 16 would be stopped for the printing of the line of information on a print line corresponding to the line instruction code.

To effectuate printing beyond the first half inch of space on a selected form length, and on a print line not corresponding to a /2 inch increment of paper advancement, at field instruction code (other than 00000) and line instruction code (other than 0000) would be trans mitted along the line 61 to theregister 64, the field instruction code being initially operative to advance the paper to the print line corresponding to the /2 inch increment next preceding the desired print line, and the line instruction code being thereafter effective, without stopping the motor, to advance the paper from such preceding /2 inch increment line to the desired print line. Upon receipt of the spacing codes in the register 64, the line decoder 90 would be responsive to the line instruction code to activate a selected line 92 to the encoder 94, the encoder 94 thereupon computing the number of l/ 120 inch motor steps required to advance the paper from the /2 inch increment line corresponding to the entered field instruction code to the desired print line, such value being entered in the step counter 100. At the outset of motor activation, the step counter 100 would be in a reset state by reason of the preceding pulse generated by the field mark disk 26, and the field mark counter 76 would contain an accumulated count corresponding to the recorded 9% inch increments'of previous paper advancement. Since the field instruction code stored in the five-digit field instruction portion of the register 64 would be of higher value than the accumulated count in the field mark counter 76, the flip flop 168 would not initially be provided with an input along the lines 80 and 82 from the field compare unit 70, and the motor step pulses generated by the disk 18 would initially be blocked from the step counter 100. It can thus be seen that during the early stage of 101010), to represent the arrival of the desired print line, the compare unit 98 would transmit a pulse along the line 110 through the NAND gates 84 to the motor stop and detent control 114, the NAND gates 84 having also been enabled by the previously mentioned pulse from the field compare unit 70, along line 80. The motor would accordingly be stopped at the desired print line for the printing of a line of information.

The following explanation is set forth to illustrative how various field instruction codes and line instruction codes would be utilized in the inventive tapeless format control system to effectuate printing on desired print lines on a selected form length. With the form select dial 41 set on the 14 inch mark as shown in FIG. 5, printing on various lines on a 14 inch form may be explained with reference to FIGS. 4 and 6. If after setting the dial 41 on the 14 inch mark, it is then desired to print a first line of information on the 5 inch line of the form, the field instruction code 01010 would be entered in the five-digit field instruction portion of the register 64, and the code 0000 entered in the line instruction portion of the register. During the resultant activation of the motor 16, the field instruction portion of the register being greater than the count in the field mark counter '76, the flip flop 168 would not be enabled by an input along the line 82 to permit the step counter 100 to count the motor step pulses generated by the disk 18, paper advancement continuing until the count in the field mark counter 76 is equal to the field instruction code (in this case both equaling 10), whereupon the field compare unit would transmit a stop pulse along the line 80 through the NAND gates 84 to the motor control unit 66, the NAND gates 84 being enabled by an input from the compareunit 98 along the line 110 by reason of the zero (or binary code 101010) state of the step counter 100. Paper advancement would accordingly terminate with the 5' inch line of the form in printing position.

If after printing the line of information on the 5 inch line, it were then desired to print four lines of information in S10 spacing immediately following the 5 inch line, the codes 01010 and 0001 would be entered in the field instruction and line instruction portions, respectively, of the register 64 for each of the desired four lines of printing. With the 0001 code in the line instruction portion of the register 64, the line decoder would activate the S10 line 92 to the encoder 94, whereupon the encoder 94 would compute and transmit to step counter a unique value for each of the four lines of printing, such values, representing the separately accumulated number of l/ l 20 inch motor steps required to produce each of the four lines of S10 spacing, being 12 steps for each line in this case. With the field mark counter 76 and the field instruction portion of the register 64 both being in a 10-equals state, the flip flop 168 would be enabled for each line of printing by an input from the field compare unit 70 along the lines 80 and 82, to thereby enable the passage of the motor step pulses from the disk 18 through the sensing circuit 122, assuming correct steps have been made, to the step counter 100. Upon the counting of 12 motor step pulses for each of the four respective lines of printing, the compare unit 98 would transmit a pulse along the line through the NAND gates 84 to the motor stop and detent control. 114, the NAND gates 84 also having been enabled by the previously mentioned pulse from the field compare unit 70.

If after printing the four lines of information in S10 spacing immediately following the inch line, it were then desired to print two lines of information in D spacing immediately following the 7 inch line on the form, the codes 01110 and 0100 would be entered in the field instruction and line instruction portions, respectively, of the register 64 for each of the desired two lines of printing, entry of the 01110 code for the first line of printing creating an unequal state between the field mark counter 76 and the field instruction portion of the register, and entry of the code 0100 for each of the two lines causing the line decoder 90 to activate the D10 line 92 to the encoder 94, the encoder 94 thereupon computing and entering in the step counter 100 a value of 24 for the first line of printing and a value of 24 for the second line, such values representing the separately accumulated number of motor steps required to produce each of the two lines of printing. In view of the unequal state of the field mark counter 76 and the field instruction portion of the register 64 during spacing for the first line, the motor step pulses from the disk 18 would initially be blocked from the step counter 100 by the flip flop 168 and four pulses generated by the field mark disk 26 would be counted by the field mark counter 76 (corresponding to the 5 /2 inch, 6 inch, 6 V2 inch and. 7 inch lines on the form). Upon the occurrence of a 14-equals state of the field mark counter 76 and the field instruction portion of the register 64 a pulse would be transmitted from the field compare unit 70 along the line 80 to the NAND gates 84, and along the line 82 to the flip flop 168, the

NAND gates 84 not being enabled by an input from the compare unit 98 due to the non-zero state of the step counter 100, the flip flop 168, however, being enabled by such pulse to permit the passage of motor step pulses from the disk 18 through the sensing circuit 122, assuming correct steps have been made, to the step counter 100. Upon the counting of 24 motor step pulses by the counter 100, the compare unit 98 would transmit a stop pulse along the line 110 through the NAND gates 84 to the motor stop and detent control 114, the NAND gates 84 being enabled by the previously mentioned input from the field compare unit 70. Advancement of the paper would accordingly be terminated for the printing of the first line of information following the 7 inch line. The codes 01110 and 0100 would then be entered in the field instruction and line insbruction portions, respectively, of the register 64 for the printing of the second line of information in D10 spacing, an enabling pulse from the field compare unit 70 being immediately transmitted to the NAND gates 84 and flip flop 168, by reason of the 14-equals state of the field mark counter and the field instruction portion of the register 64, the motor step pulses from the disk 18 being accordingly passed through the sensing circuit 122, then to the flip flop 168, assuming a correct step has been made, and finally inputted to and counted by the step counter 100. Upon the occurrence of a zero-equals state in the step counter 100 representing 24 steps completed, the compare unit 98 would transmit a stop pulse along the line 110 through the enabled NAND gates 84 to the motor stop and detent control 114, to thereby terminate paper advancement for the printing of the second line of information in D10 spacing.

If after printing the two lines of information in D10 spacing immediately following the 7 inch line on the form, it were then desired to print two lines of information in S8 spacing immediately following the 8 inch line, the codes 10000 and 0010 would be entered in the field instruction and line instruction portions, respectively, of the register 64 for each of the two lines of printing, spacing for the first line of printing involving the initial counting of two pulses from the field mark disk 26 by the counter 76 (corresponding to the 7 1/2 inch and 8 inch lines), and the subsequent counting of 15 motor step pulses from the disk 18 by the step counter 100 (to create a zero-equals state in the step counter 100 representing 15 steps completed), when a 16-equals state occurs in the field mark counter 76 and the field instruction portion of the register 64, as previously described. Upon entering the codes 10000 and 0010 for the second lines of S8 printing, the flip flop 168 would be enabled immediately by an input along the line 82 resulting from the 16-equals state of the field mark counter 76 and the field instruction portion of the register 64, the step counter 100 proceeding to count the motor step pulses from the disk 18. Upon the counting of 15 additional motor step pulses by the counter 100 therein (such being the value computed by the encoder 94 and stored in the step counter 100 upon entry of the code 0010 for the second line of printing), a pulse would be transmitted from the compare unit 98 along the line 110 through the enabled NAND gates 84 to the motor stop and detent control 114, to thereby terminate paper advancement for the printing of the second line of information in S8 spacing.

If after printing the two lines of information in S8 spacing immediately following the 8 inch line on the form, it were then desired to print one line of information on the 13 inch line and one line of information in T6 spacing immediately following the 13 inch line, the codes 11010 and 0000 would be entered in the field instruction and line instruction portions, respectively, of the register 64 for printing on the 13inch line, and the codes 11010 and 1001 would be entered in the respective portions of the register 64 for the printing of the second line in T6 spacing. Entry of the 11010 and 0000 codes would result immediately in the transmission of an input pulse from the compare unit 98 to the NAND gates 84, by reason of the O-equals state of the step counter 100, the field mark counter '76 proceeding to count ten pulses from the field mark disk 26 (corresponding to the 8 /2 inch, 9 inch, 9 V2 inch, 10 inch, 10 /2 inch, 11 inch, 11 /2 inch, 12 inch, 12 /2 inch and 13 inch lines on the form), and the field compare unit serving to transmit a pulse to the NAND gates 84 upon the occurrence of a 26-equals state in the field mark counter 76 and the field instruction portion of the register 64, the NAND gates 84 being thereby enabled to pass a pulse to the motor stop and detent control 114 to terminate paper advancement for the printing of the line of information on the 13 inch line of the form. Upon the entry of the 11010 and 1001 codes in the respective portions of the register 64, for the printing of the second line of information in T6 spacing, the flip flop 168 would immediately receive an input along the line 82 from the field compare unit 70, due to the 26- equals state of the field mark counter 76 and the field instruction portion of the register 64, the step counter being thereby rendered enabled to count the motor step pulses from the disk 18. Upon the counting of 60 motor step pulses by the counter 100, such being the value computed by the encoder 94 and entered in the 

1. A tapeless format control apparatus for controllably printing lines of information according to preselected formats on selected form lengths of a web paper in a printer, said printer having web paper handling and positioning means associated with a printing position thereof, said apparatus comprising: a. a stepping motor for operatively advancing said web paper relative to said printing position, said motor being coupled to said web paper handling and positioning means, b. motor control means associated with said stepping motor and effective for stopping and detenting said stepping motor, c. means for selecting one of a predetermined plurality of form lengths upon whIch said lines of information are to be printed, said form length selecting means including: an elongated cylindrical gear coupled to said web paper handling and positioning means, a plurality of rotatably mounted and variable slotted gears of predetermined varied diameters gearably coupled to said elongated cylindrical gear, first slot sensing means associated with each of said plurality of slotted gears, and means for adjustably activating selected slots of selected ones of said slotted gears to thereby operatively represent a selected one of said plurality of form lengths, d. first pulse generating means associated with said form length selecting means and responsive to the sensing of said adjustably activated selected slots to thereby identify the passage of said selected slots past said associated sensing means during the rotation of said selected gear and to identify the passage of corresponding selected form lengths past said printing position, e. means for receiving and storing externally originated print spacing instructions, f. second and third pulse generating means respectively effective for identifying each increment of advancement of said web paper and each increment of rotational motion of said stepping motor according to a gray coded scheme, g. means cooperating with said motor control means and responsive to said print spacing instructions for controllably coordinating said plurality of identifying pulses from said first, said second and said third pulse generating means such that each line of information printed on said selected form length is properly spaced from the preceding line and all of the lines of printed information conformed to a selected one of said preselected formats, said coordinating means including: sensing means responsive to said second pulse generating means effective for identifying each increment of rotational motion of said stepping motor and cooperating with said motor control means for allowing said stepping motor to increment only upon ascertaining that its preceding increment was properly executed, and first comparator means responsive to said print spacing instructions and interacting with said motor control means for controllably retarding the speed of said stepping motor as a print line on said selected form length of said web paper corresponding to said print spacing instructions approaches said printing position.
 2. The format control apparatus defined in claim 1 wherein the slots formed in each of said plurality of slotted gears are arranged on one or more rings, each ring containing from one to three spaced apart slots according to the diameter of the related slotted gear and the form lengths to be represented thereby, the arrangement of slots along all of the rings on a given slotted gear permitting the selection of a primary form length corresponding to the circumference of the gear or the selection of one or more submultiples of said primary form length corresponding to proportional angular rotations of said given gear to bring angularly displaced slots on the rings into sensing relationship relative to said first slot sensing means associated therewith.
 3. The format control apparatus defined in claim 2 wherein said first slot sensing means of said form length selecting means comprises: a plurality of sets of one or more photo-cells and light sensitive switches cooperably associated with said plurality of variably slotted gears, each set being associated with a separate one of said gears and including a photo-cell and a light sensitive switch cooperably disposed relative to each ring along which the slots thereof are arranged.
 4. The format control apparatus defined in claim 3 wherein said means for adjustably activating selected slots of selected ones of said slotted gears comprises: a. a switching member interconnected with said plurality of sets of photo-cells and light sensitive switches of said first slot sensing means and providing a mutually exclusive terminal for given ORed coMbinations of the photo-cells and their associated light sensitive switches, each of said terminals representing a different selectable form length, b. an activatable selection verifying device coupled to said switching member, c. a first adjustable member bearing form length indications and effective for connecting a selected terminal of said switching member to said selection verifying device, and d. a second adjustable member effective for rotating said elongated cylindrical gear and said plurality of variably slotted gears such that the slot of said slotted gears corresponding to a selected form length is operatively aligned with its associated photo-cell and light sensitive switch as evidenced by the activation of said selection verifying device.
 5. The format control apparatus defined in claim 4 wherein said first pulse generating means comprises a plurality of serially coupled NOR-NAND gates forming a part of the interconnection of said switching member with said plurality of sets of photo-cells and light sensitive switches of said first slot sensing means, said plurality of gates being arranged in sets corresponding to said sets of photo-cells and light sensitive switches associated with said plurality of variably slotted gears, each of said sets of gates providing interconnection as between a set of photo-cells and light sensitive switches and a number of terminals of said switching member corresponding to the number of photo-cells and light sensitive switches in the respective set.
 6. The format control apparatus defined in claim 3 wherein said means for receiving and storing said print spacing instructions comprises: a shift register having a field skip portion for temporarily storing a binary decimal code indicative of the number of increments of web paper advancement that are required in an initial skipping phase thereof, and a line advance portion for storing a binary decimal code indicative of the number of increments of rotational motion of the stopping motor that are required in a line advance phase of said web paper advancement.
 7. The format control apparatus defined in claim 6 wherein said second pulse generating means effective for identifying each increment of advancement of said web paper during said initial skipping phase thereof comprises: a. a first multi-slotted disk coupled to said web paper handling and positioning means in contiguous relationship with said elongated cylindrical gear, and b. a second slot sensing means comprised of a photo-cell and a light sensitive switch, said second slot sensing means being coupled to said pulse coordinating means and disposed in cooperating relationship with said first multi-slotted disk.
 8. The format control apparatus defined in claim 7 wherein said third pulse generating means effective for identifying each increment of rotational motion of said stepping motor according to said gray coded scheme comprises: a. a second disk of two rings of multi-slots coupled to a motor shaft of said stepping motor, and b. a third slot sensing means comprised of at least two photo-cells and two light sensitive switches arranged in parallel, said third slot sensing means being coupled to said pulse coordinating means and disposed in cooperating relationship with said second disk.
 9. The format control apparatus defined in claim 7 wherein said first disk is provided with sixteen radially disposed and equally spaced-apart slots, the movement of each slot into cooperating relationship with said second slot sensing means representing a 1/2 inch increment of web paper advancement.
 10. The format control apparatus defined in claim 8 wherein said second disk is provided with 24 radially disposed and equally spaced-apart coded positions per ring in gray code and said third slot sensing means is provided with two parallelly arranged photo-cells and light sensitive switches, the movement of each of said coded positions into cooperating relationship with each Of said photo-cells and light sensitive switches representing a 15* angular displacement of said stepping motor as translated into a 1/120 inch increments of web paper advancement.
 11. The format control apparatus defined in claim 7 wherein said means for controllably coordinating said plurality of identifying pulses from said first, said second and said third pulse generating means comprises: a. first counter means associated with said plurality of variably slotted gears and said first slot sensing means and with said first disk and said second slot sensing means, b. second comparator means operatively coupled to said first counter means and to said field skip portion of said register, c. value determining means associated with and coupled to said line advance portion of said register, d. second counter means associated with said first disk, said second slot sensing means, said sensing circuit means, and said value determining means, and e. first gating means coupled to said first and said second comparator means and effective for outputting a pulse to said motor control means to thereby stop said stepping motor when both said comparator means output a pulse concurrently.
 12. The format control apparatus defined in claim 11 wherein said first counter means is resettably responsive to pulses generated by said plurality of slotted gears, said first slot sensing means, and said plurality of serially coupled NOR-NAND gates of said first pulse generating means, and advanceably responsive to pulses generated by said first disk and said second slot sensing means.
 13. The format control apparatus defined in claim 11 wherein said second counter means is resettably responsive to pulses generated by said first disk and said second slot sensing means and advanceably responsive in a count down sequence to pulses generated by said sensing circuit means after having been initialized by a pulse from said value determining means, said count down sequence starting a selected initialization point and reduceably advancing from said selected point to zero.
 14. The format control apparatus defined in claim 13 wherein said second counter means is provided with initializing means responsive to said value determining means and effective for setting said second counter means upon the concurrent receipt of pulses from said sensing circuit means and from said second comparator means.
 15. The format control apparatus defined in claim 13 wherein said sensing circuit means comprises: a. sensor gating means coupled to said second disk and said third slot sensing means and effective for decoding gray coded signals received therefrom, b. sensor storage means responsive to initialization by said sensor gating means and effective for storing a pulse representative of the preceding increment of advancement of said stepping motor, c. sensor compare means coupled to said sensor gating means and said sensor storage means and effective for outputting a pulse whenever the gray coded signal received by said sensor gating means and representing the present step is the next correct step when compared with the preceding step as indicated by said sensor storage means, and d. pulse triggering means biased by said sensor compare means and effective upon receipt of a pulse therefrom for triggering said sensor storage means, said second counter means and said first comparator means.
 16. The format control system defined by claim 15 wherein said sensor gating means and said sensor compare means are NAND gates.
 17. The format control system defined by claim 15 wherein said sensor storage means and said pulse triggering means are gated flip-flops.
 18. The format control apparatus defined in claim 11 wherein said value determining means comprises: a. a decoder coupled to said line advance portion of said register and effective for decoding a binary coded signal stored therein to thereby activate a selected one of a plurality of output channels corresponding to said binary coded signal, said binary coded signal being representative of a predetermined line advance instruction, and b. an encoder coupled to said decoder by means of said plurality of output channels and coupled also to said second counter means, said encoder being effective for computing a value representative of the number of incremental motor steps required to execute said predetermined line advance instruction and to initialize said value in said second counter means upon the receipt of concurrent signals from said first comparator means and from said sensing circuit means.
 19. The format control apparatus defined in claim 18 wherein said first comparator means comprises: a. second gating means coupled to receive signals from said second counter means and effective for outputting a plurality of unique signals to said motor control means to thereby initiate or terminate stepping motor incrementing, b. third gating means coupled to receive signals from said second counter means and effective for outputting a signal when said second counter means has reached a predetermined point in its downcounting to zero, c. latching means coupled to said third gating means and effective for outputting a signal upon receipt of a signal therefrom, and d. braking means coupled to said latching means and to said sensing circuit means and effective upon receiving concurrent signals therefrom to output fixed and variable period signals to said motor control means to thereby enable braking and reduced speed powering of the stepping motor, respectively.
 20. The format control system defined in claim 19 wherein said second gating means and said third gating means are NAND gates.
 21. The format control system defined in claim 19 wherein said latching means is a flip-flop.
 22. The format control system defined in claim 19 wherein said braking means is a gated delayed multivibrator.
 23. The format control apparatus defined in claim 19 wherein said motor control means comprises sets of gating circuits equal in number to the number of phases of said stepping motor, each of said sets being comprised of a plurality of gates according to the number of functions that are to be performed by said stepping motor, the outputs of said gating sets being ORed together to output a control pulse upon the concurrent receipt of input pulses from said first comparator means and said sensing circuit means, said output pulses serving to activate corresponding motor drive means to thereby energize the desired phase windings of said stepping motor.
 24. The format control system defined in claim 23 wherein said function gates are NAND gates.
 25. The format control apparatus defined in claim 18 wherein said means for controllably coordinating said plurality of identifying pulses additionally comprises: fourth gating means coupled to said first pulse generating means and said plurality of slotted gears and first slot sensing means, and coupled also to said decoder by means of a predetermined one of said output channels thereof, said fourth gating means being coupled further to a manually operable skip control unit effective for advancing said web paper in the absence of a binary coded signal in either said field skip or line advance portions of said register, the enabling of said fourth gating means by a pulse generated by said first pulse generating means and a pulse from either said skip control unit or said decoder being effective to output a signal to said motor control means to thereby terminate said incremented movement of said stepping motor.
 26. The format control apparatus defined in claim 25 wherein said fourth gating means is comprised of NAND gates.
 27. In a line printer having format control apparatus for controllably printing lines of information according to preselected formats on selected form lengths of a web paper, said printer having web paper handling and positioning means, a stepping motor coupled To said web paper handling means, and motor control means for stopping and detenting said motor, and said format control apparatus having form length selecting means effective for selecting a predetermined plurality of form lengths, means for receiving and storing externally originated print spacing instructions consisting of a field advance portion and a line advance portion for governing the placement of each line of printed information on the selected form length and for skipping to the heading of a succeeding form, first and second determining means for determining the number of incremental advancements of the web paper and the number of incremental steps of the stepping motor required by said field advance portion and said line advance portion of said print spacing instruction to thereby advance the web paper from the preceding to the next succeeding line of printed information, first and second counting means for counting the incremental advancements of said web paper as directed by said field advance portion of said stored print spacing instruction and the incremental steps of said stepping motor as directed by said line advance portion of said stored print spacing instruction, and means cooperating with said motor control means to stop and detent said stepping motor when the number of incremental advancements of the web paper and the number of incremental steps of the stepping motor as counted by said first and said second counting means equals the number of incremental advancements and the number of incremental steps determined by said first and said second determining means, said form length selecting means comprising: a. a driven shaft forming a part of said web paper handling and positioning means and coupled to and responsive to said stepping motor, b. an elongated gear coupled to said driven shaft, c. a plurality of rotatably mounted and variably slotted gears of predetermined varied diameters cooperably disposed relative to said elongated gear, predetermined slots formed in said gears representing predetermined ones of said predetermined plurality of form lengths, d. slot sensing means associated with each of said plurality of slotted gears, e. means for adjustably activating selected slots of said plurality of variably slotted gears such that a predetermined one of said plurality of form lengths is selected, and f. means responsive to said adjustable slot activating means and effective for generating an identifying pulse whenever a selectively activated slot is sensed by its associated slot sensing means, said pulse serving to reset said first counting means and to enable said motor control means to stop and detent said motor upon completion of a skip to heading instruction received and stored in said receiving and storing means.
 28. The format control apparatus defined in claim 27 wherein the slots formed in each of said plurality of slotted gears are arranged on one or more rings, each ring containing from one to three spaced apart slots according to the diameter of the related slotted gear and the form lengths to be represented thereby, the arrangement of slots along all of the rings on a given slotted gear permitting the selection of a primary form length corresponding to the circumference of the gear or the selection of one or more submultiples of said primary form length corresponding to proportional angular rotations of said given gear to bring angularly displaced slots on the rings into sensing relationship relative to said slot sensing means associated therewith.
 29. The format control apparatus defined in claim 28 wherein said slot sensing means comprises: a plurality of sets of one or more photo-cells and light sensitive switches cooperably associated with said plurality of variable slotted gears, each set being associated with a separate one of said gears and including a photo-cell and a light sensitive switch cooperably disposed relative to each ring along which the slots thereof are arranged.
 30. The format control apparatus defined in claim 29 wherein said means for adjustably activating selected slots of said plurality of variably slotted gears comprises: a. a switching member interconnected with said plurality of sets of photo-cells and light sensitive switches of said slot sensing means and providing a mutually exclusive terminal for given ORed combinations of the photo-cells and their associated light sensitive switches, each of said terminals representing a different selectable form length, b. an activatable selection verifying device coupled to said switching member, c. a first adjustable member bearing form length indications and effective for connecting a selected terminal of said switching member to said selection verifying device, and d. a second adjustable member effective for rotating said elongated cylindrical gear and said plurality of variably slotted gears such that the slot of said slotted gears corresponding to a selected form length is operatively aligned with its associated photo-cell and light sensitive switch as evidenced by the activation of said selection verifying device.
 31. The format control apparatus defined in claim 30 wherein said pulse generating means comprises a plurality of serially coupled NOR-NAND gates forming a part of the interconnection of said switching member with said plurality of sets of photo-cells and light sensitive switches of said slot sensing means, said plurality of gates being arranged in sets corresponding to said sets of photo-cells and light sensitive switches associated with said plurality of variably slotted gears, each of said sets of gates providing interconnection as between a set of photo-cells and light sensitive switches and a number of terminals of said switching member corresponding to the number of photo-cells and light sensitive switches in the respective set. 